Integrated position and direction system with map display oriented according to heading or direction

ABSTRACT

An integrated position and direction system is disclosed that includes a digital compass and a satellite positioning system (SATPOS) having a receiver adapted to receive satellite position determining signals. Direction is determined using the digital compass and heading is determined using the SATPOS. The integrated position and direction system is operable to display, on a display device, map information that is oriented according to a current orientation regardless of whether the system is stationary or moving. The map display is oriented according to either heading determined using the satellite positioning system or direction determined using the digital compass. The integrated position and direction system updates the map display to orient the map display with a current position. Moreover, the integrated position and direction system updates the map display to orient the map display with a current orientation (e.g., heading or direction).

CROSS REFERENCE TO RELATED APPLICATION

This patent application is a Continuation-in-Part of commonly-owned U.S.patent application Ser. No. 09/614,392, filed on Jul. 12, 2000, now U.S.Pat. No. 6,353,798, entitled “INTEGRATED POSITION AND DIRECTION SYSTEMWITH THREE-SENSOR DIGITAL COMPASS”, by Green et al., which isincorporated herein by reference.

TECHNICAL FIELD

This invention relates to the field of map display systems.Specifically, the present invention relates to a method and apparatusfor displaying map information which is oriented according a currentorientation.

BACKGROUND ART

Satellite positioning system (SATPOS) devices that determine positionusing the satellites of the US Global Positioning System (GPS) arecommonly used for navigation of vessels, vehicles, airplanes, and otherconveyances. SATPOS devices are also used for surveying, constructionsite planning and management, mining, oil and gas exploration anddevelopment, etc. Also, handheld SATPOS devices are used for personalnavigation, data collection, data maintenance, etc.

SATPOS devices are quite effective for indicating the position of theSATPOS device. Position is typically indicated using either analphanumeric indication of position or by displaying a map thatindicates position. Alphanumeric indications of position typicallyinclude coordinates such as, for example, Latitude and Longitude, WorldGeodetic Survey (WGS) Coordinates, etc.

Map displays typically indicate position by an icon or other indicatorvisible on a map. One such map display, typically referred to as amoving map display, displays the position of the SATPOS in the center ofthe displayed map. Such map displays typically are oriented such thatthe top of the SATPOS device's display indicates North (either magneticNorth or true North). That is, irrespective of the direction in whichthe SATPOS device is actually oriented, North is shown at the top of thedisplay. For users that intuitively know which direction is North, suchmaps are adequate for locating features displayed on the map. However,for users that do not know where North is, or when visibility isobscured such that the user cannot determine where North is, such mapsare inadequate for guiding the user to a destination or feature on themap.

For many commercial applications of SATPOS systems, such as constructionsite planning and management, surveying, navigation, etc., it isessential that an operator be able to locate features displayed on themap. Such users typically operate a separate device for indicatingdirection such as a conventional magnetic compass.

Some SATPOS devices indicate the direction of movement of the SATPOSdevice, typically referred to as “heading”. Typically, heading isdetermined by analysis of determined position in relation to priordeterminations of position as the SATPOS moves. Typically, SATPOSdevices that indicate heading use a map display oriented such that thetop of the SATPOS unit (e.g., the top of the unit's display) correspondsto North (either magnetic North or true North).

Some prior art SATPOS devices orient the displayed map such that the topof the SATPOS unit (e.g., the top of the unit's display) corresponds tothe direction of movement calculated by the SATPOS device. This gives agood approximation of the user's heading as long as the user continuesto move and as long as the SATPOS unit is oriented in the direction ofmovement, allowing a user to easily determine the location of featuresvisible on the display.

However, when the SATPOS device stops moving, determination of headingcan no longer be made. Some SATPOS systems maintain the previous headingfor orienting the moving map display for a given time interval. Otherprior art SATPOS systems default to positioning North at the top of themap. This can be quite confusing to the user.

Recently, digital compasses have been developed that can indicatedirection. However, digital compasses must be calibrated to properlyalign the digital compass prior to use. Also, each time that magneticenvironment around the compass changes, the digital compass must berecalibrated. Digital compasses are typically calibrated by moving thedigital compass in a full horizontal arc. The calibration process takestime and is prone to operator error. Also, calibration error can occuras a result of local magnetic anomalies.

Typically, a map display has map information which is oriented accordingto a default orientation (e.g., North, South, East, West, etc.).However, if the orientation of a user is different from the defaultorientation, the user of the map information needs to rotate the mapdisplay in order to properly read the map display. For example, if themap display is oriented towards the North and the user is moving towardsthe South or is oriented towards the South, the user must rotate the mapdisplay by 180 degrees to properly read the map display. Unfortunately,it may be difficult, inconvenient, or hazardous to rotate the mapdisplay.

What is needed is a method and apparatus for providing an accurateindication of heading to a user of a SATPOS device. Also, a method andapparatus is needed that meets the above needs and that accuratelyindicates direction when the SATPOS is not moving. Also, a method andapparatus is needed that is easy to use and that does not require a userto manually calibrate a compass. Also, a method and apparatus is neededthat facilitates generating a map display that is oriented according toa current orientation so that to improve readability and understandingof the map display regardless of whether the SATPOS is stationary ormoving. The present invention meets the above needs.

DISCLOSURE OF THE INVENTION

The present invention provides a method and apparatus that accuratelyindicates direction and heading to a user of a satellite positioningsystem (SATPOS) device. The integrated position and direction system ofthe present invention includes a digital compass for indicatingdirection when the SATPOS is not accurately determining direction. Inone embodiment, the digital compass is comprised of at least threesensors.

An integrated position and direction system is disclosed that includes aSATPOS having a receiver adapted to receive satellite positiondetermining signals. The integrated position and direction system of thepresent invention also includes a digital compass that is adapted todetermine direction.

The integrated position and direction system also includes a controllerfor controlling the operations of the integrated position and directionsystem. The controller is coupled to the SATPOS, the digital compass,and to a display.

In one embodiment of the present invention, when the SATPOS is moving,the direction of movement or “heading” determined by the SATPOS isindicated on the display. When the SATPOS is not moving, the directiongiven by the digital compass is indicated on the display. Therefore,while the SATPOS is moving, the heading is indicated, and when theSATPOS is not moving, direction is indicated using the digital compass.Thus, the present invention provides a method and apparatus forproviding an accurate indication of both heading and direction to a userof a SATPOS device.

In one embodiment, the digital compass is automatically calibrated bythe SATPOS when the SATPOS is moving. This calibration can be initiatedby the user or can be fully automatic. More particularly, the digitalcompass of the present invention is calibrated automatically, either asa result of user input (e.g., selection of an icon, pressing of abutton, etc.), or as a result of user-defined criteria for automaticcalibration. That is, the user can program the present invention toautomatically calibrate the digital compass (e.g. when velocity exceedsa given threshold, whenever the SATPOS begins moving, periodically whilethe SATPOS is moving, when the difference between the SATPOS determinedheading differs from the heading indicated by the digital compass bymore than a predetermined threshold, etc.) Thus, the position anddirection system of the present invention is easy to use because thereis no need for a user to calibrate a compass as is required using aprior art compass alone.

The present invention also provides a method and apparatus (e.g.,integrated position and direction system) for displaying map informationthat is oriented according to a current orientation. The integratedposition and direction system includes a display device for displaying amap display that is oriented according to either heading determinedusing the satellite positioning system or direction determined using thedigital compass. In particular, when the integrated position anddirection system is moving, heading is utilized to orient the mapdisplay. However, when the integrated position and direction system isnot moving, direction is utilized to orient the map display. In analternate embodiment, direction is utilized to orient the map display ifthe integrated position and direction system is moving or if theintegrated position and direction system is not moving.

The integrated position and direction system updates the map display toorient the map display with a current position. Moreover, the integratedposition and direction system updates the map display to orient the mapdisplay with a current orientation (e.g., heading or direction). Thus, auser can read and understand the map display without the need forrotating the integrated position and direction system because the mapdisplay is oriented to correspond with the user's perception of his/herphysical environment.

These and other objects and advantages of the present invention will nodoubt become apparent to those of ordinary skill in the art after havingread the following detailed description of the preferred embodimentsthat are illustrated in the various drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

FIG. 1 is a diagram of a position and direction system in accordancewith one embodiment of the present invention.

FIG. 2 is a diagram of an embodiment of the position and directionsystem of FIG. 1 in accordance with one embodiment of the presentclaimed invention.

FIG. 3 is a perspective view of an embodiment of the position anddirection system of FIG. 2 in accordance with one embodiment of thepresent claimed invention.

FIG. 4 is a diagram of a position and direction system in accordancewith one embodiment of the present claimed invention.

FIG. 5 is a flow chart illustrating a method for indicating directionand heading in accordance with one embodiment of the present invention.

FIG. 6A is a diagram showing an exemplary display that indicatesposition and heading in accordance with one embodiment of the presentclaimed invention.

FIG. 6B is a diagram showing an exemplary display that indicatesposition and direction in accordance with one embodiment of the presentclaimed invention.

FIG. 7A is a diagram showing an exemplary display that indicatesposition and heading in accordance with one embodiment of the presentclaimed invention.

FIG. 7B is a diagram showing an exemplary display that indicatesposition and direction in accordance with one embodiment of the presentclaimed invention.

FIG. 8A is a diagram showing an exemplary display that indicatesposition and heading in accordance with one embodiment of the presentclaimed invention.

FIG. 8B is a diagram showing an exemplary display that indicatesposition and direction in accordance with one embodiment of the presentclaimed invention.

FIG. 9 is a diagram showing an exemplary display that indicates positionand heading in accordance with one embodiment of the present claimedinvention.

FIG. 9B is a diagram showing an exemplary display that indicatesposition and direction in accordance with one embodiment of the presentclaimed invention.

FIG. 10 is a flow chart illustrating a method for calibrating a digitalcompass in accordance with one embodiment of the present invention.

FIG. 11 is a schematic representation of an exemplary configuration fora 3-Sensor magnetic sensor in accordance with one embodiment of thepresent claimed invention.

FIG. 12 is a flow chart illustrating a method of displaying mapinformation that is oriented according to a current orientation inaccordance with an embodiment of the present invention.

FIGS. 13A-13D show exemplary map displays in accordance with anembodiment of the present invention.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be obvious toone of ordinary skill in the art that the present invention may bepracticed without these specific details. In other instances, well knownmethods, procedures, components, and circuits have not been described indetail as to not unnecessarily obscure aspects of the present invention.

FIG. 1 is a logical representation of components of integrated positionand direction system 100 in accordance with one embodiment of thepresent invention. Integrated position and direction system 100 includesSatellite Positioning System (SATPOS) 3 that is operable for determiningposition. In one embodiment, SATPOS 3 is adapted to determine positionusing a Satellite Positioning System such as the U.S. Global PositioningSystem (GPS).

In operation, SATPOS 3 determines the location of SATPOS 3 by analysisof satellite position determining signals such as signals fromsatellites of the U.S. GPS. Position signal processing circuitry inSATPOS 3 also determines the direction of movement of SATPOS 3, referredto hereinafter as “heading” and couples the determined heading tocontroller 1. In the present embodiment, heading is determined bycomparing satellite position determining signals received as theintegrated position and direction system 100 moves.

Integrated position and direction system 100 of FIG. 1 also includesdigital compass 4. Digital compass 4 is operable to determine directionand couple direction to controller 1. More particularly, in the presentembodiment, digital compass 4 determines the compass direction thatcorresponds to the orientation of the integrated position and directionsystem 100.

Continuing with FIG. 1, controller 1 controls the operation ofintegrated position and direction system 100. In one embodiment,controller 1 is a general-purpose computer. Alternatively, controller 1is an integrated circuit device such as a microcontroller or anApplication Specific Integrated Circuit (ASIC) device or a FieldProgrammable Gate Array (FPGA) device. In one embodiment, the functionsof controller 1 are performed by a general purpose microprocessor thatis operable to execute instructions contained in one or more softwareprogram(s).

In the present embodiment, controller 1 is operable to display thedetermined position and the determined direction and/or heading ondisplay 2. Display device 2 may be a liquid crystal device, flat paneldisplay, or other display device suitable for creating graphic imagesand alpha numeric characters recognizable to the user.

FIGS. 2-3 show an embodiment of the present invention that isincorporated into a handheld portable housing. That is, the housing issmall enough to fit into a user's hand.

Referring now to FIG. 2, integrated position and direction system 200 isshown to include SATPOS 3 that is operable for determining position. Inthe present embodiment, SATPOS 3 includes SATPOS antenna 10, SATPOSreceiver 11, and SATPOS processor 12. In one embodiment, SATPOSprocessor 12 is a GPS processor made by Trimble Navigation, Ltd. ofSunnyvale, Calif. In this embodiment, SATPOS antenna 10 is an ACE IIGPS™ antenna, manufactured by Trimble Navigation, Ltd. and SATPOSreceiver 11 includes a SIERRA GPS™ chipset, manufactured by TrimbleNavigation, Ltd. Although such a specific implementation is described,the present invention is also well suited to an embodiment havingvarious other components and features.

Referring still to FIG. 2, microprocessor 20, in conjunction withdirection program 22 perform the functions of controller 1 of FIG. 1.That is, in the present embodiment, direction program 22, operable onmicroprocessor 20 controls the operations of integrated position anddirection system 200. In the present embodiment, microprocessor 20 is ageneral-purpose microprocessor that has low power consumption such as,for example, a Motorola RISC microprocessor made by Motorola Inc., ofAustin, Tex. Alternatively, other types of processors, an ASIC device ora FPGA device can be used.

Continuing with FIG. 2, power source 24 provides power to the variouscomponents of integrated position and direction system 200. Power source24 may be any suitable power source that is light-weight and compactsuch as, for example, built-in rechargeable batteries, AA batteries orAAA batteries.

Data storage device 25 is coupled to controller 20 and is adapted tostore data. Data that can be stored in data storage device 25 includes,for example, an operating software program such as direction program 22.Data storage device 25 may be any type of digital data storage medium.In one embodiment, data storage device 25 is a Random Access Memory(RAM) device such as, for example, a Static Random Access Memory (SRAM)device, a Dynamic Random Access Memory (DRAM) device. Alternatively,other types of memory storage devices such as flash memory, tape, CDROM, or DVD may be used.

Referring still to FIG. 2, connection mechanism 21 is coupled tomicroprocessor 20 and is adapted to connect to external devices such as,for example external computers. This allows for easily and quicklydownloading new programs for operation on microprocessor 20 and allowsfor updating direction program 22. In one embodiment, connectionmechanism 21 is a connector that complies with the RS-232 standard.

With reference again to FIG. 2, display device 28 is also electricallycoupled to microprocessor 20. In one embodiment, display device 20 is anactive matrix liquid crystal display. Alternatively a cathode ray tube,or other display device suitable for creating graphic images andalphanumeric characters recognizable to the user can be used.

Input device 27 is coupled to microprocessor 20 and allows for couplinguser input to microprocessor 20. In the present embodiment, input device27 includes function keys and an alphanumeric keypad. Alternatively,input device 27 includes a trackball, mouse, touch pad, joystick. Thepresent invention is also well suited to receiving user input by othermeans such as, for example, voice commands.

Referring now to FIG. 3, an embodiment of position and direction system200 is shown that is incorporated into housing 30 that is small enoughto hold in a user's hand. In the present embodiment, function keys 32and alphanumeric keypad 33 allow for coupling user input to position anddirection system 200. In one embodiment, one or more of function keys 32operates as a cursor control device. That is, one or more of functionkeys 32 allows the computer user to dynamically signal thetwo-dimensional movement of a visible symbol (cursor) on the displayscreen of display device 28.

FIG. 4 shows an embodiment of the present invention in which SATPOSprocessor 12 is used for controlling the operations of the integratedposition and direction system 400. Because SATPOS processor 12 is usedfor controlling the operations of integrated position and directionsystem 400, there is no need for a second microprocessor such asmicroprocessor 20 of FIG. 2.

In the embodiment shown in FIG. 4, SATPOS processor 12 is operable todetermine position and heading using SATPOS signals and is also operableto receive direction determined by digital compass 4. In thisembodiment, SATPOS processor 12 includes instructions for determiningwhich source of direction signals (heading from SATPOS signals ordirection determined by digital compass 4) is to be indicated (e.g.,displayed) on display device 28. In the present embodiment, theseinstructions are contained in direction program 42 that controls theoperations of integrated position and direction system 400. Directionprogram 42 is a computer program that is operable on SATPOS processor12. However, alternatively, instructions necessary for the operation ofintegrated position and direction system 400 can be implemented on anASIC, a FPGA, or similar device.

In the present embodiment, position is indicated on display device 28.In one embodiment, position is indicated alphanumerically using latitudeand longitude. Alternatively, position is indicated by an icon displayedon a moving map display. The integrated position and direction system400 includes a data storage 25.

In the present embodiment, reference to a satellite positiondetermination system, or “SATPOS” herein refers to a Global PositioningSystem (GPS), to a Global Orbiting Navigation Satellite System(GLONASS), to a hybrid system that is capable of using satellites fromthe GPS and the GLONASS, and to any other positioning system, includingpseudolites, that provide signals that can be used to determineposition. The term “satellite position determination system” and“SATPOS” as used herein, is intended to include position determinationusing pseudolites or equivalents of pseudolites, and the term “satelliteposition determination system signals” and “SATPOS signals,” as usedherein, is intended to include position determination system-likesignals and data from pseudolites or equivalents of pseudolites. Also,signals from other sources such as LORAN, Wide Area Augmentation System(WAAS) satellites, etc. may be used to determine position.

In the embodiments shown in FIGS. 1-4, digital compass 4 is used todetermine direction. In the present embodiment, digital compass 4 is acompass that determines direction by detection of electromagnetic flux.In the present embodiment, digital compass 4 is a magnetic field sensormade by Honeywell, Inc. Any of a number of different types ofcommercially available digital compasses can be used.

Referring now to FIG. 11, a schematic representation of a magnetic fieldsensor 1100 in accordance with one embodiment of the present inventionis shown. In this embodiment, magnetic field sensor 1100 is comprised,in part, of three sensors 1102, 1104, and 1106. By having three sensors,magnetic field sensor 1100 is able to determine the elevation angle ofintegrated position and direction system 100 of FIG. 1. Morespecifically, in one embodiment, sensors 1102 (x-direction sensor) and1104 (y-direction sensor) determine the azimuthal orientation ofintegrated position and direction system 100. However, the determinationof azimuthal orientation will be determined with the assumption thatintegrated position and direction system 100 is held level. Thus, if,for example, a user of integrated position and direction system 100 iswalking up a steep hill; walking down a steep hill; holding theintegrated position and direction system 100 in a vertically orientedmanner; and the like, the accuracy of the determined azimuthalorientation may be severely compromised. By using magnetic field sensor1100 which includes sensor 1106 (z-direction sensor), the presentembodiment is able to correctly determine the azimuthal orientation ofintegrated position and direction system 100 by correcting for anyvariation from horizontal in the position of integrated position anddirection system 100. That is, sensor 1106 of the present embodimentdetermines the variance in integrated position and direction system 100from a truly horizontal position. It will be understood that in therepresentation of FIG. 11, when integrated position and direction system100 is at a truly horizontal position, sensor 1106 will be verticallyoriented. Although a specific schematic implementation is shown in FIG.11, the present invention is well suited to use with any of a number ofdifferent types of commercially available digital compasses whichcompensate for variations from a horizontal orientation.

Referring still to FIG. 11, in one embodiment, in addition to correctingthe determined azimuthal orientation of integrated position anddirection system 100 for variance from a truly horizontal orientation,the present invention also determines (and optionally displays) theelevation angle of integrated position and direction system 100. In suchan embodiment, the user is made aware not only of the accurate azimuthalorientation (i.e. the direction in which integrated position anddirection system 100 is pointed), but the user is also informed of theelevation angle at which integrated position and direction system 100 isoriented. Hence, the user can determine, for example, the slope of ahill by holding integrated position and direction system 100 parallel tothe surface of the hill and reading the determined elevation angle.Additionally, although magnetic field sensor 1100 is comprised, in part,of three orthogonally oriented sensors 1102, 1104, and 1106 in thepresent embodiment, the present invention is also well suited to anembodiment in which more than three sensors are used and to anembodiment in which the plurality of sensors are arranged other thanorthogonally.

FIG. 5 shows a method for indicating direction and heading according toone embodiment of the present invention. As shown by steps 501-502, whenthe SATPOS is moving, heading is determined using the SATPOS. In thepresent embodiment, a satellite positioning system including a receiveradapted to receive satellite position determining signals such as, forexample, SATPOS 3 of FIGS. 1-4 is used to both determine whether theSATPOS is moving and to determine heading.

In one embodiment of the present invention, the determination of whetherthe SATPOS is moving (step 501) is made by comparing the velocity ofmovement to a threshold velocity. In the present embodiment, priordeterminations of position are compared to the most recent determinationof position, along with the time of each determination of position todetermine the velocity of movement of the SATPOS. When the velocity isdetermined to be greater than the threshold velocity, the SATPOS isconsidered to be moving.

As shown by step 505 of FIG. 5, when the SATPOS is moving, heading isindicated using the heading determined in step 502. In the embodimentshown in FIG. 1, display device 2 is used to indicate heading; and inthe embodiment shown in FIGS. 2-3, display device 28 is used to indicateheading.

Still referring to FIG. 5, when the SATPOS is not moving, as shown bysteps 501 and 503, direction is determined using the digital compass. Inthe present embodiment digital compass 4 of FIGS. 1-4 is used fordetermining direction.

As shown by step 506 of FIG. 5, when the SATPOS is not moving, directionis indicated using the direction determined by the digital compass instep 503. In the embodiment shown in FIG. 1, display device 2 is used toindicate direction; and in the embodiment shown in FIGS. 2-3, displaydevice 28 is used to indicate direction.

The indications of direction and heading steps 505-506 can take any of anumber of different forms. In one embodiment, heading and direction areindicated using a displayed compass rose. That is, icons representing acompass rose are displayed on, for example, display device 2 of FIG. 1or display device 28 of FIGS. 2-3.

In one embodiment of the present invention the direction and headingindicated in steps 505-506 are indicated using a four-point compassrose. That is, direction is indicated relative to the compass points ofNorth(N), South(S), East(E), and West(W). FIGS. 6a-6 b show exemplarydisplays 600 a-600 b that include a four-point compass rose that can beused to indicate either heading (step 505 of FIG. 5) or direction (step506 of FIG. 5).

Referring now to FIGS. 6a-6 b, in the present embodiment, an icon isused to indicate whether heading is being displayed or whether directionis being displayed. More particularly, in display 600 a of FIG. 6a, icon602 is displayed to indicate to the user that heading is beingdisplayed. Referring now to FIG. 6B, display 600 b indicates thatdirection is being displayed. That is, the absence of icon 602 of FIG.6A indicates that the digital compass is being used and that directionis being displayed.

In the embodiments shown in FIGS. 6A-6B, the compass rose is displayedsuch that direction and heading are indicated relative to alignment mark601. That is, the compass rose is rotated such that the proper directionor heading is always indicated by reference to alignment mark 601. Thus,in the embodiment shown in FIG. 6A, because the compass point of N isaligned with alignment mark 601, display 600 a indicates that the SATPOShas a heading directly to the North. Similarly, in the embodiment shownin FIG. 6B, because the compass point of N is aligned with alignmentmark 601, display 600 b indicates a North direction. That is, the SATPOSis oriented such that alignment mark 601 is pointing directly to theNorth.

FIGS. 7A-7B shown an embodiment in which direction and heading areindicated using an eight-point compass rose. That is, direction andheading are indicated relative to the compass points of North(N), South(S), East (E), West (W), North East (NE), South East (SE), South West(SW), and North West (NW).

Referring now to FIGS. 7A-7B, exemplary displays 700 a and 700 b areshown to include an eight-point compass rose that can be used toindicate either heading (step 505 of FIG. 5) or direction (step 506 ofFIG. 5). As in the embodiment shown in FIGS. 6A-6B, direction andheading are indicated relative to alignment mark 601 and icon 602indicates whether direction or heading is being displayed.

In the embodiment shown in FIG. 7A, because the compass point of E isaligned with alignment mark 601, and because icon 602 is displayed,display 700 a indicates that the SATPOS has a heading directly to theEast. Similarly, in the embodiment shown in FIG. 7B, because the compasspoint of E is aligned with alignment mark 601, and because icon 602 isnot displayed, display 700 b indicates an East direction. That is, theSATPOS is oriented such that the top of the display, as indicated byalignment mark 601, is pointing directly to the East.

FIGS. 8A-8B show an embodiment in which both a four point compass roseand an eight-point compass rose are used. In the present embodiment, thedisplay of a four-point compass rose indicates that heading (step 505 ofFIG. 5) is being displayed while the display of an eight-point compassrose indicates that direction (step 506 of FIG. 5) is being displayed.In the embodiment shown in FIGS. 8A-8B, direction and heading areindicated relative to the top of the display, as indicated by alignmentmark 601. It should be understood that the compass rose can beimplemented with any number of points (e.g., a 16-point compass rose,etc.).

Now referring to display 800 a of FIG. 8A, because the compass point ofE is aligned with alignment mark 601, and because a four-point compassrose is displayed, display 800 a indicates that the SATPOS has a headingdirectly to the East. Similarly, in the embodiment shown in FIG. 8B,because the compass point of E is aligned with alignment mark 601, andbecause an eight-point compass rose is displayed, display 800 bindicates a East direction. That is, the SATPOS is oriented such thatthe top of the display, as indicated by alignment mark 601 is pointingin the cardinal direction of East.

The apparatus and method of the present invention automatically switchesbetween displays of heading and direction as the SATPOS moves and stopsmoving. Thus, the method and apparatus of the present invention providean uninterrupted display that can be used to find features, waypoints,etc. In the present embodiment, either heading or direction iscontinually displayed.

In the present embodiment, the determined position is also indicated. Inthe embodiment shown in FIGS. 6A-8B, position is indicatedalphanumerically using latitude and longitude as shown by icon 610.Alternatively, position is indicated by an icon displayed on a movingmap display.

In one embodiment of the present invention, position, direction andheading are indicated using a moving map display. FIGS. 9A-9B shows anexemplary display 900 that includes position icon 920 that indicates theposition of the SATPOS relative to icons 910-912 that representfeatures. In the present embodiment, icon 910 indicates the position ofa feature that is a fire hydrant, icon 911 indicates the position of afeature that is a tree, and icon 912 indicates the position of a featurethat is a building.

Referring now to FIGS. 9A-9B, exemplary displays 900 a and 900 b areshown to include position icon 920 that indicates the position of theSATPOS relative to features 910-912. As in the embodiment shown in FIGS.6A-7B, an icon 602 is displayed to indicate whether direction or headingis being displayed. In the present embodiment, an icon 921 thatindicates the direction of North is also displayed so that the user candetermine the orientation of the moving map display.

Referring now to FIG. 9A, an exemplary display 900 a is shown thatindicates a heading of North. That is, because heading icon 602 isdisplayed, a display of heading is indicated (step 505 of FIG. 5).Because the map is oriented such that the North icon is pointed to thetop of the display, the heading is indicated as being directly to theNorth.

Referring now to FIG. 9B, an exemplary display 900 b is shown thatindicates a direction of West. That is, because heading icon 602 is notdisplayed, a display of direction is indicated (step 506 of FIG. 5).Because the map is oriented such that the North icon is pointed to theright side of the display, the direction is indicated as being directlyto the West. That is, the display is oriented such that the top of thedisplay points in the cardinal direction of West.

The apparatus and method of the present invention automatically switchesbetween displays of heading and direction as the SATPOS moves and stopsmoving. Thus, the method and apparatus of the present invention providean uninterrupted display that can be used to find features such as, forexample, features 910-912 of displays 900 a-900 b.

The present invention is well adapted for other indications of headingand direction other than those shown in FIGS. 6A-9B. In one embodiment,heading and/or direction are indicated using an indication of degreesfrom 0 to 360 degrees. That is, a number is displayed on the displaydevice that indicates cardinal direction with 0 and 360 being North.That is, in the embodiment shown in FIG. 1, display device 2 displays anumber from 0 to 360; and in the embodiment shown in FIGS. 2-3, displaydevice 28 displays a number from 0 to 360.

The embodiments shown in FIGS. 1-9B of the present invention provide amethod and apparatus for providing an accurate indication of directionand heading to a user of a SATPOS device. When the user is stationary,orientation is accurately indicated using a digital compass. When theuser is moving, the direction of movement(heading) is accuratelyindicated. Because the integrated position and direction system of thepresent invention always indicates either heading or direction, the useris always able to locate features, waypoints, etc.

Prior art digital compasses are typically calibrated manually byrotating the digital compass in a circular arc. The digital compass ofthe present invention can be manually calibrated using this technique.

In one embodiment of the present invention the digital compass isautomatically calibrated using the SATPOS determination of heading. Inone embodiment of the present invention, the digital compass isautomatically calibrated upon selection of an icon or button thatindicates “Automatic Compass Calibration” when the position anddirection system of the present invention is moving (e.g. when step 501of FIG. 5 indicates that the SATPOS is moving).

In one embodiment of the present invention, the digital compass isautomatically calibrated on a periodic basis, without any required inputfrom the operator, when the SATPOS is moving. In one embodiment, thedigital compass is automatically calibrated according to user selectabletime periods. In the present embodiment, the user can select timeperiods of ten minutes, 30 minutes, one hour, four hours, or 12 hours.Thus, for example, when a user selects a time period of ten minutes, thedigital compass is calibrated when the digital compass begins to moveand every ten minutes thereafter until the digital compass stops moving.This provides for easily maintaining the accuracy of the digitalcompass.

In the present embodiment, the digital compass is calibrated bydetermining heading using the SATPOS, and adjusting the directionindicated by the digital compass according to the heading determined bythe satellite positioning system. In the embodiment shown in FIG. 1,controller 1 is operable to automatically calibrate the digital compass;in the embodiment shown in FIGS. 2-3, direction program 22 is operableto automatically calibrate the digital compass; and in the embodimentshown in FIG. 4, direction program 42 is operable to automaticallycalibrate the digital compass.

FIG. 10 shows a method for calibrating a digital compass 1000 in which adigital compass (e.g. digital compass 4 of FIGS. 1-4) is calibratedusing a heading determined using a SATPOS (e.g., SATPOS 3 of FIGS. 1-4).Referring now to step 501 a the velocity determined by the SATPOS iscompared to a threshold velocity. If the velocity is not greater thanthe threshold velocity (steps 501 a and 503), direction is determinedusing the digital compass(step 503), and direction is indicated as shownby step 506.

Continuing with FIG. 10, if the velocity is not greater than thethreshold velocity, heading is determined using the SATPOS as shown bysteps 501 a and 502. The heading determined using the SATPOS is thenindicated as shown by step 505.

Still referring to FIG. 10, as shown by step 550, the heading indicatedby the digital compass is determined. In the embodiment shown in FIG. 1,controller 1 is operable to determine the heading indicated by thedigital compass using input from digital compass 4; in the embodimentshown in FIGS. 2-3, direction program 22 is operable to determine theheading indicated by the digital compass; and in the embodiment shown inFIG. 4, direction program 42 is operable to determine the headingindicated by the digital compass.

The heading indicated by the digital compass is then compared to theheading determined using the SATPOS as shown by step 550B. If thedifference between the heading determined using the SATPOS and theheading indicated by the digital compass by more than a predeterminederror threshold, the digital compass is calibrated as shown by steps550B-551. In one embodiment, a default error threshold of between one totwo percent is initially used, which can be altered by the user at anytime to accommodate the needs of that particular user. The presentembodiment allows for the automatic calibration of the digital compasswhenever the heading indicated by the digital compass significantlyvaries from the heading determined using the SATPOS.

As discussed above, the present invention provides for automaticallycalibrating a digital compass, either as a result of user input (e.g.,selection of an icon, pressing of a button, etc.), or as a result ofuser-defined criteria for automatic calibration. That is, the user canprogram the present invention to automatically calibrate the digitalcompass (e.g. when velocity exceeds a given threshold, whenever theSATPOS begins moving, periodically while the SATPOS is moving, when thedifference between the SATPOS determined heading differs from theheading indicated by the digital compass by more than a predeterminedthreshold, etc. The integrated position and direction system of thepresent invention is easy to use since there in no need for a user tomanually calibrate the digital compass.

Though the embodiments shown in FIGS. 1-9B describe the indication ofeither direction or heading, the present invention is well adapted fordisplay of both direction and heading when the SATPOS is moving.

In an embodiment, the integrated position and direction system 100 ofFIGS. 1-4 is capable of displaying map information. In particular, themap information is stored in a data storage device 25 (FIG. 2). The datastorage device 25 can be any type of data storage medium (e.g., RAM,SRAM, DRAM, hard drive, CD ROM, DVD, etc.). The map information isdisplayed on a display device 28 (FIG. 3). In practice, the integratedposition and direction system 100 utilizes the map information togenerate a map display 900A and 900B (FIGS. 9A-9B). The map display 900Ais oriented according to a current orientation, whereas the currentorientation is either heading determined using the satellite positioningsystem 3 (SATPOS) or direction determined using the digital compass 4.

The integrated position and direction system 100 updates the map display900A to orient the map display 900A with a current position determinedusing the SATPOS 3. Moreover, the integrated position and directionsystem 100 updates the map display 900A to orient the map display 900Awith a current orientation (e.g., heading or direction) determined usingeither the SATPOS 3 or the digital compass 4. Thus, a user can read andunderstand the map displays 900A and 900B without the need for rotatingthe integrated position and direction system 100 because the mapdisplays 900A and 900B are oriented to correspond with the user'sperception of his/her physical environment regardless of whether he/sheis stationary or moving.

In other words, the map displays 900A and 900B show a properrepresentation of the location of any map information with respect tothe user 920. In FIG. 9A, the integrated position and direction system100 and the user are moving towards the North, thus, the map display900A is oriented according to the heading of North. In FIG. 9B, theintegrated position and direction system 100 and the user are orientedtowards the West, thus, the map display 900B is oriented according tothe direction of West.

FIG. 12 is a flow chart illustrating a method 1200 of displaying mapinformation that is oriented according to a current orientation inaccordance with an embodiment of the present invention. In particular, amap display is generated on the display device 28 of the integratedposition and direction system 100. In an embodiment, the method 1200 isimplemented by a programmed integrated position and direction system100.

At step 1205, the method in accordance with an embodiment of the presentinvention begins.

As shown in step 1210, the integrated position and direction system 100determines position using the satellite positioning system 3 (SATPOS).

Continuing with step 1215, the integrated position and direction system100 determines whether the integrated position and direction system 100is moving or whether the integrated position and direction system 100 isnot substantially moving. The term “not substantially moving” indicatesthat the integrated position and direction system 100 is not moving, isonly moving a small amount, or is not moving sufficiently to enabledetermination of heading.

If it is determined that the integrated position and direction system100 is moving, at step 1220 the integrated position and direction system100 determines heading using the SATPOS 3. Otherwise, at step 1225, theintegrated position and direction system 100 determines direction usingthe digital compass 4.

In an alternate embodiment, the integrated position and direction system100 determines direction both when the integrated position and directionsystem 100 is moving and when the integrated position and directionsystem 100 is not substantially moving.

Referring to step 1230, the integrated position and direction system 100generates a map using the map information stored in the data storagedevice 25 and using the determined position. In an embodiment, theprocessor of the integrated position and direction system 100 performsthis step.

As shown by step 1235, the integrated position and direction system 100orients the map according to the current orientation determined in step1220 or step 1225. If the integrated position and direction system 100determined heading, the map is oriented according to heading determinedwith the SATPOS 3. If the integrated position and direction system 100determined direction, the map is oriented according to directiondetermined with the digital compass 4.

With reference to step 1240, the integrated position and directionsystem 100 displays the map on the display device of the integratedposition and direction system 100 to form a map display which isoriented according to heading or direction, whereas the location of theuser is shown on the map display. In an embodiment, the integratedposition and direction system 100 also displays the determined positionand displays either heading or direction.

At step 1245, the integrated position and direction system 100determines whether to update the map display if a change in heading ordirection has occurred. The integrated position and direction system 100can be programmed to update the map display upon any type of change inheading or direction. For example, the integrated position and directionsystem 100 can be programmed to update the map display upon heading ordirection changes that exceed a predetermined threshold. In anotherexample, the integrated position and direction system 100 can beprogrammed to update the map display upon heading or direction changesthat exceed a threshold that is dependent on the display scale of themap display. Alternatively, the integrated position and direction system100 can be programmed to update the map display upon heading ordirection changes of any amount.

If the map display needs to be updated, the method returns to step 1210and continues as described above. Otherwise, the method proceeds to step1250.

Referring to step 1250, the integrated position and direction system 100determines whether to update the map display if a change in currentposition has occurred. The integrated position and direction system 100can be programmed to update the map display upon any type of change incurrent position. For example, the integrated position and directionsystem 100 can be programmed to update the map display upon currentposition changes that exceed a predetermined threshold. In anotherexample, the integrated position and direction system 100 can beprogrammed to update the map display upon current position changes thatexceed a threshold that is dependent on the display scale of the mapdisplay. Alternatively, the integrated position and direction system 100can be programmed to update the map display upon current positionchanges of any amount.

If the map display needs to be updated, the method returns to step 1210and continues as described above. Otherwise, the method proceeds to step1255.

As shown by step 1255, the integrated position and direction system 100monitors the current orientation and the current position to determinewhether to update the map display. Monitoring criteria can be providedto the integrated position and direction system 100 to specify themanner and circumstances in which to perform the monitoring of thecurrent orientation and the current position.

The method returns to step 1245 while the integrated position anddirection system 100 monitors the current orientation and the currentposition. Otherwise, at step 1260 the method in accordance with anembodiment of the present invention ends.

As illustrated by FIG. 12, the integrated position and direction system100 changes the map display to orient the map display according to acurrent orientation (e.g., heading or direction), enabling the user toeasily read and understand the map display without forcing the user tomentally reorient the map display as in the prior art.

FIGS. 13A-13D show exemplary map displays 1300A-1300D in accordance withan embodiment of the present invention. Each exemplary map display1300A-1300D includes an alignment mark 601, a position display fordisplaying the determined position, a map information display 660, and aheading and direction indicator 650. The heading icon 602 indicates thatthe heading and direction indicator 650 is indicating heading ratherthan direction.

The heading and direction indicator 650 can include any number ofdifferent configurations. In one embodiment, the heading and directionindicator 650 is a four-point compass rose that is oriented according toheading or direction. In another embodiment, the heading and directionindicator 650 is an eight-point compass rose that is oriented accordingto heading or direction. In yet another embodiment, the heading anddirection indicator 650 is an indication of degrees from 0 to 360degrees that is oriented according to heading or direction. Heading isdetermined using the SATPOS 3 as discussed above. Direction isdetermined using the digital compass 4 as discussed above.

The map information display 660 includes the map information (e.g.,location of map landmarks 910-912 and location of the user 920)discussed with respect to FIGS. 9A and 9B.

In FIG. 13A, the map display 1300A is oriented according to the headingof North, whereas the heading icon 602 is displayed. Hence, the headingand direction indicator 650 aligns North with the alignment mark 601.Moreover, the map information display 660 is oriented according to theheading of North, as illustrated in FIG. 9A.

In FIG. 13B, the map display 1300B is oriented according to thedirection of South, whereas the heading icon 602 is not displayed.Hence, the heading and direction indicator 650 aligns South with thealignment mark 601. Moreover, the map information display 660 isoriented according to the direction of South.

In FIG. 13C, the map display 1300C is oriented according to the headingof West, whereas the heading icon 602 is displayed. Hence, the headingand direction indicator 650 aligns West with the alignment mark 601.Moreover, the map information display 660 is oriented according to theheading of West, as illustrated in FIG. 9B(showing direction of West).

In FIG. 13D, the map display 1300D is oriented according to thedirection of East, whereas the heading icon 602 is not displayed. Hence,the heading and direction indicator 650 aligns East with the alignmentmark 601. Moreover, the map information display 660 is orientedaccording to the direction of East.

It should be understood that the map display can be oriented accordingto orientations other than North, South, West, or East, so that to showthe current orientation to enable a user to easily read and understandthe map display.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the claims appended hereto and theirequivalents.

What is claimed is:
 1. A method of displaying map information using anintegrated position and direction system (IPADS) having a satellitepositioning system and a digital compass, said method comprising thesteps of: a) determining position using said satellite positioningsystem; b) determining orientation, said orientation determined usingsaid satellite positioning system when said IPADS is moving and saidorientation determined using said digital compass when said IPADS is notmoving; c) generating said map information using said positiondetermined in said step a); d) displaying said map information such thatsaid map information is oriented according to said orientationdetermined in said step b); and e) indicating whether said orientationis determined using said satellite positioning system or whether saidorientation is determined using said digital compass.
 2. A method asrecited in claim 1 further comprising the step of: updating said mapinformation displayed in step d) upon movement of said IPADS and uponchanges in orientation of said IPADS such that said map informationdisplayed in step d) indicates a current position of said IPADS andindicates a current orientation of said IPADS.
 3. A method as recited inclaim 1 wherein said step c) includes reading information stored in adata storage device.
 4. A method as recited in claim 1 furthercomprising the step of: displaying a four-point compass rose that isoriented according to said orientation determined in said step b).
 5. Amethod as recited in claim 1 further comprising the step of: displayingan eight-point compass rose that is oriented according to saidorientation determined in said step b).
 6. A method as recited in claim1 further comprising the step of: displaying an indication of degreesfrom 0 to 360 degrees that is oriented according to said orientationdetermined in said step b).
 7. A method as recited in claim 1 whereinsaid map information displayed in said step d) includes an icon thatindicates said position determined in said step a).
 8. In a computersystem having a processor, a data storage device, a satellitepositioning system, and a digital compass, a computer-implemented methodof displaying map information comprising the steps of: a) determiningposition using said satellite positioning system; b) determiningorientation, said orientation determined using said satellitepositioning system when said computer system is moving and saidorientation determined using said digital compass when said computersystem is not moving; c) generating said map information using saidposition determined in said step a); d) displaying said map informationsuch that said map information is oriented according to said orientationdetermined in said step b); and e) indicating whether said orientationis determined using said satellite positioning system or whether saidorientation is determined using said digital compass.
 9. Acomputer-implemented method as recited in claim 8 further comprising thestep of: updating said map information displayed in step d) uponmovement of said computer system and upon changes in orientation of saidcomputer system such that said map information displayed in step d)indicates a current position of said computer system and indicates acurrent orientation of said computer system.
 10. A computer-implementedmethod as recited in claim 8 wherein said step c) includes readinginformation stored in a data storage device.
 11. A computer-implementedmethod as recited in claim 8 further comprising the step of: displayinga four-point compass rose that is oriented according to said orientationdetermined in said step b).
 12. A computer-implemented method as recitedin claim 8 further comprising the step of: displaying an eight-pointcompass rose that is oriented according to said orientation determinedin said step b).
 13. A computer-implemented method as recited in claim 8further comprising the step of: displaying an indication of degrees from0 to 360 degrees that is oriented according to said orientationdetermined in said step b).
 14. A computer-implemented method as recitedin claim 8 wherein said map information displayed in said step d)includes an icon that indicates said position determined in said stepa).
 15. An integrated position and direction system (IPADS) comprising:a) a satellite positioning system for determining position and fordetermining heading using satellite position determining signals; b) adigital compass for determining direction; c) a data storage device forstoring map information; d) a display device; e) a processor coupled tosaid satellite positioning system, coupled to said digital compass,coupled to said display device, and coupled to said data storage device,wherein said processor is operable to generate a display on said displaydevice using said map information and using said position determined bysaid satellite positioning system, said display oriented according tosaid heading determined using said satellite positioning system whensaid IPADS is moving, and wherein said display is oriented according tosaid direction determined using said digital compass when said IPADS isnot substantially moving; and f) an indicator for indicating whethersaid display is oriented using said satellite positioning system orwhether said display is oriented using said digital compass.
 16. Anintegrated position and direction system as recited in claim 15 whereinsaid satellite positioning system uses satellites of the U.S. GlobalPositioning System to determine said position and to determine saidheading.
 17. An integrated position and direction system as recited inclaim 15 further comprising a housing, said satellite positioningsystem, said digital compass, said data storage device, and saidprocessor disposed in said housing.
 18. An integrated position anddirection system as recited in claim 17 wherein said housing ispalm-sized.
 19. An integrated position and direction system (IPADS)comprising: a) a satellite positioning system for determining positionand for determining heading using satellite position determiningsignals; b) a digital compass for determining direction; c) a datastorage device for storing map information; d) a display device; e) aprocessor coupled to said satellite positioning system, coupled to saiddigital compass, coupled to said display device, and coupled to saiddata storage device, wherein said processor is operable to generate adisplay on said display device using said map information and using saidposition determined by said satellite positioning system, said displayoriented according to one of said direction determined using saiddigital compass and said heading determined using said satellitepositioning system; and f) an indicator for indicating whether saiddisplay is oriented using said satellite positioning system or whethersaid display is oriented using said digital compass.
 20. An integratedposition and direction system as recited in claim 19 wherein saidsatellite positioning system uses satellites of the U.S. GlobalPositioning System to determine said position.
 21. An integratedposition and direction system as recited in claim 19 further comprisinga housing, said satellite positioning system, said digital compass, saiddata storage device, and said processor disposed in said housing.
 22. Anintegrated position and direction system as recited in claim 21 whereinsaid housing is palm-sized.